Ceramic articles and method of producing them



www@ Jana 49 A F GORTON CERAMIC ARTICLES AND METHOD OF PRODUCING THEM Filed April 9, 1925 Patented' p Jan. 4, 1927..

l UNITED STA-TES 'PATENTS OFFICE.

ARTHUR FEDDEMAN GORTON, OF BERWYN, ILLINOIS, ASSIGNOR TO WESTERN ELEC- TRIC COMPANY, INCORPORATED, OF YORK, v1\l'. Y., A CORPORATION OF NEW YORK.

CERAMIC ARTICLES AND METHOD OF PRODUCING THEIVL Application ined april a, 1925.` serial No. 21,788.

This invention relates to improved ceramic articles and improved methodsl of producing them.

ln the production of articles, such as crucibles and linings therefor it Iis desirable 4to employ a comparatively large amount of coarse material which is non-plastic and highly refractory. The reason for this is two-fold. First when the article is formed by molding it is desirable that the shrink\ -age be reduced to a minimum. 'lhis effect can be obtained by using a comparatively small amount of plastic clay as a binder, the remainder being material which has already been fired. The tiredy material which is employed is also preferably coarse because it has been found in practice that when this material is coarse the article is much less apt to crack when heated or cooled quickly. lt is obvious that if the plastic method of forming articles is employed the amount ofv coarse material use-d is limited because at least enough plastic material must be re tained so that the composition is moldable. Second, if the` static slip' or casting method is employed the refractory material must bev in finely divided form or it will not float or be held in suspension in the slip, but lwill sink to the bottom thereof. Owing to .the difficulties encountered in these two methods of forming crucibles and the like a method sometimes employed has been to mix the highly refractory materials with anorganic binder such as ntar or molasses, mold the resultingr mixture into the 'desired shape and then fire it in order to`remove the or# ganic binder.,

Objectsof the present-.invention are to produce an improved ceramic article and to provide an improved method of forming such articles. j

'In producing an article in accordance with the invention a plaster of Panis mold. correto be produced is rotate-d on a vertical axis and a slip of the desired composition and consistency having a coarse grained :relativel ly heavy material as a constituent'is introduced into the mold. Due to the rotation the slip is caused to flow up around the iside walls of the mold Where sucient moisture isV absorbed by the plaster of Paris to cause a solid precipitation thereon, the`coarse (lil Fig. 2 is a perspective view of a inishedav article embodying the invention.

Referring now to the accompanying drawing which shows apparatus by means of which the method may be practiced, the numeral 10 refers generally to the main frame Aof a machine and is flared at its lower portion to form a base plate 11 which is secured to any 'desirable` foundation by suitable means such as anchor bolts 12. A shaft 15 leading to a source of power not shown) is rotatably journaled, in a vertical portion of the frame 10 and has secured to one eX- tremity thereof a driving disk 16 which driving disk may be secured to the shaft 15 by suitable means such as a retaining nut 17. A. second shaft 20 is rotatably journaled in horizontal portions of the frame 10 at 21 and 22, the shaft 20 having secured to its upper portion afunold-hol'ding member 23.

A driven disk 25 `is keyed tothe shaft 20 in a keyway 26and is adjustable thereon by means 0f the elongated character of the key- Way. Suitable means such as a set screw '27 is provided for securing the driven disk 25` to the desirable portion of the shaft 20. 'llhe sides of the mold-holding member 23 are sloped inwardly so that a mold 32 of absorbent material such as plaster of Paris,

,as it is rotated, may be secured to the up'Q x sponding to the'outsideshape of the article bae plate 35, .whichmay be provided for that purpose. When the mold is revolved the slip including the clay binder and coarse material is driven outwardly against the side `Walls of the mold and when the moisture 'posit of the thiclin has been absorbed `the resulting article 40 will take a shape somewhat as shown in the drawing.

In practicing the invention, a mold such as the one shown in the accompanying drawing is suitably rotated on a vertical axis as described above and a suitable quantity of. slip inserted. therein to obtain a deess desired. The slip which is employed may contain a comparatively small amount -of ceramic binder and a largepercentage of coarse material, such as carborundum, chrome, VZircon, zirconia, silicon carbide, magnesia and the like. The centrifugal force which is caused by the rotation of the mold will cause the coarse material to creep up around the side walls of the mold and as the water is absorbed through the walls thereof the coarse grog and binder will adhere to the lateral s ur' face of the mold, the two materials vbelng distributed evenly.

The region where the greatest deposition of solid material takes place will depend to a large eatent upon the speed with which thainold is rotated. lf the speed is very great, a large portion of the solid material will be deposited on the lateral surface of the mold and the bottom will be proportionately thin or of substantially the same thickness as the walls. This condition may be very desirable where a refractory lining is being formed for a crucible such as for a graphite crucible which is used in induction corrosionmay occur at the bottom of the crucible than at the top. When'producing a crucible of this general character it will be noted that the outer part thereof can -take an eccentric shape whereas the interior surface will correspond toa true parabola which is a desirable shape for the interior of such crucibles to possess.

By means of the present method crucibles can be formed of thin cross section which is desirable because crucibles of this charling molten metals, because a porous crucible will permit metal to enter. the pores thereof, and so increase the rate of corrosion.

What is claimed is:

`1. A refractory article,vcentrifugally cast from a slip containing a coarse grained material. Y

2. A walled article containing' a coarse grained material evenly distributed therein, and centrifngally cast from a slip.'

3. A walled article cast from a slip which contains uniformly distributed portions of a relatively heavy material, the -walled article having a portion of the interior wall thereof of a parabolic shape im arted thereto solely by the rotation of a ody of slip during the casting thereof.

4. A method of casting a walled article which consists in rotatin at a predetermined/ speed around an axis a body of slip containing portions of relatively heavy material to cause the slip to assume a predetermined shape with the material uniformly distributed 4therein, simultaneously therewith removing some of the'moisturettherefrom to retain the material in its uniform distribution, and thereafter removing the remainder of the moisture.

il 5. A method of casting a refractor article which consists in rotating a bo yv of slip containing coarse grog, and simultaneously therewith extracting moisture therefrom until the coarse grog is uniformly distributed in the sli .and the body thereof becomes self-sustaining.

In witness whereof, l hereunto subscribe my name this 23rd day of March, A. Dl 

